Piano-forte



G. CADDICK.

PIANO FORTE.

(No Model.)

No. 454,204. PatentedJune 16,1891.

Il l w im WITNESSES.

UNITED STATES PATENT OEEICE.

GEORGE CADDICK, OF AIJLEGIIENY, PENNSYLVANIA.

PIANO-FORTE.

SPECIFICATION forming part of Letters Patent No. 454,204, dated June 16,1891.

Application filed April 15, 1889. Serial No. 307,236. (No model.)

To all whom, t may concern:

Be it known that I, GEORGE OADDICK, of the city of Allegheny, in thecounty of Allegheny and -State of Pennsylvania, have invented a new anduseful Improvement in Piano-Fortes, of which the following is a full,clear, and exact description.

I shall describe my improvement with ret'- erence to the accompanyingdrawings, in which- Figure l is a plan View of the sound-board of thepiano provided with my improvement. Fig. 2 is a cross-section on theline II II of Fig. l. Fig. 3 is a vertical section on the line III IIIof Fig. l. Fig. Je is a section on the line IV IV of Fig. l.

Like symbols of reference indicate like parts in each of the figures.

It is a known principle in acoustics that if a tuning-fork of a certainpitch be put in vibration and held to the mouth of an organpipe whosetone corresponds to the tuningfork in pitch the pipe will be putinvibration and will produce a sound ot' the same pitch as .thetuning-fork, the vibration of the tuning-fork being in exact relation tothe air in the pipe, and that if a tuning-fork be put in vibration andset on a hollow tube or box open at the end and containing the relativecubic inches of air required in a pipe to produce a sound of the samepitch as the tuning'- fork the tone of the fork Will be augmented andmodified by the vibrations imparted to the air in the tube. Theseprinciples are embodied in my improved apparatus, which I will nowproceed to describe, and which consists in combining with the strings ofapiano air-tubes of corresponding pitch, which are adapted to respondthereto.

In the application of the invention I prefer to construct the tubes bypartitioning the space between the sound-board and the backframe board,by which means I am enabled to support the strings out of line on anelevated bridge set on the sound-board, thereby obtaining a more solidbearing of the strings on the bridge and imparting their full vibrationto the sound-board and underlying tluepipes. These partitions consist,preferably, of interposed wooden strips glued to the backframe and soundboard, thus forming flues orpipes, which may be made of exactly thesizeA and proportion required, and which are preferably open at the endnearest the wrestplank and closed at the end nearest. the bridge,though, if desired, the openings may be formed next to the bridge andthe closed ends situate at the wrest-plank. I prefer the constructionIirst named, because I am thereby enabled to obtain much better resultsthanif the closed ends are at the Wrest-plank. A sound-board thusconstructed does not require any ribs, because the partitions formingthe lues or pipes answer the same purpose and impart to the structurestrength sufcent to support the bridge.

It is not only-requisite that the tube shall contain the number ot cubicinches of air necessary to produce the tone needed, but that the openend of the pipe shall be oi' proper proportion, and I iind I obtain thebest result when the area ot' the openingis the fiftyseventh or onehundred and fifteenth part oi the area of the interior of the pipe.

Referring to the drawings, A represents the sound-board.

C is the back-trame board.

D is the Wrest-plank.

E E are the bridges set on the soundboard.

F is the usual iron frame, which is firmly secured to the back-frameboard by anumber of screws or bolts at the margin of the frame. Inaddition to such bolts I provide, also, a series of bolts F', extendingthrough the hitchpin strip of the iron frame into a supportingplank F2.This series of bolts imparts great stiffness and strength to the 'frameof the piano.

The partitions I3 between the soui'id-board and the back-board ailord anumber ot flues or pipes under the strings, and the proper rela-tivedimensions of such pipes are secured by spacing the partitions at properdistances from each other, and for the treble-strings of the pi anothere can be employed further plank pieces or plates C and C2 placed onthe backframe board to reduce the dimensions of the flue to the properdegree. The construction and relative arrangement of the tubes andstrings are clearly illustrated in the several figures of the drawings.Each tube has an LII ICO

opening b at the end next the fiest-plank, and corresponding openings bare made in the iron frame to register with the openings l). It will beobserved that toward the base part oi the piano and in the over-stringbass, the space being limited, it becomes necessary for each of theseveral tubes,which I have designated by the reference-figure B', toanswer for several tones. The air-spaces of these tubes may becalculated to the simplest relative soundsuch as octaves, fifths, andfourths, adding the thirds Where the space will admit of itleaving theremaining tones to vibrate in sympathy with them. The tubes respond bysympathetic vibration, and are scaled similar to organ-pipes to properlengths and breadths. For the treble and middle strings of the piano Iemploy a tube for each set of strings or tone arranged according to thechromatic scale, except that for the` last octave I may omit thepartitions altogether.

It is not absolutely necessary for the tubes to be immediately under theset of strings to which they respond, as I iind they will respond ifsome distance away; but it is desirable to have them placed as near tothe strings they belong as the scale of the piano Will admit.

My invention may be applied either to uprlght or grand pianos, and itsadvantages in securing` fullness of tone will be appreciated by theskilled musician. In pianos of the construction heretofore employedthere has always been dflicult-y experienced in that the sound-board intimeloses its elasticity, thereby inj uriously affecting the tone of thepiano. In my improved construction,where the air-tubes take the place ofthe sound-board, this cannot happen. I am also enabled by the use of thepartitions to obtain a strong support for the bridges, and thereby toprevent the evil consequences resulting from sinkin ot' the bridge awayfrom the strings.

My invention is susceptible of modilication in form, proportions, anddetails of construe tion by those skilled in the art.

lVhat I claim isn l. In a piano -forte, the combination, with thesoundboard and strings, of pipes or flues in contact with thesound-board and arranged in position to receive the vibrations of thestrings and corresponding thereto in pitch, said strings being arrangedoutside the pipes or iiues, substantially as and for the purposesdescribed.

2. In a piano-forte, the combination, with the sound-board and strings,of pipes underlying and in contact with the sound-board andcorresponding in pitch to the strings, substantially as and for thepurposes described.

3. In a piano -forte, the combination, with the sound-board and strings,of pipes underlying andin contact with the sound-board and correspondingin pitch to the strings, said pipes being open at one end and closed atthe other, substantially as and for the purposes described.

4. The combination of the sound-board and back frame, interposedpartitions connecting

